Beijing, China - China vowed Tuesday it would impose "countermeasures" if US President Donald Trump made good on his threat to impose new tariffs linked to his war on Iran.

Trump – who is scheduled to visit Beijing next month for talks with counterpart Xi Jinping – said Sunday he would hit China's goods with a 50% tariff if it provided military assistance to Tehran.

His comments came the same day US outlet CNN reported that US intelligence indicated China was preparing to deliver new air defence systems to Iran within the next few weeks, citing three people familiar with the assessments.

Over the weekend, The New York Times quoted US officials as saying US intelligence suggested Beijing might have already sent a shipment of shoulder-fired missiles.

Chinese foreign ministry spokesman Guo Jiakun said those reports were "completely fabricated" during a news conference on Tuesday.

"If the US insists on using this as an excuse to impose additional tariffs on China, China will definitely take resolute countermeasures," Guo said.

China is a key economic partner of Iran – it buys most of the Middle Eastern country's oil.

But the countries have no formal military pact, and many analysts say Beijing largely sees the relationship between the two as transactional.

China also has strong economic ties to the Gulf countries and has criticized Iran's attacks on them over the course of the war.

Meanwhile, a US-sanctioned tanker believed to be linked to China reportedly passed through the Strait of Hormuz despite a maritime blockade declared by the President Donald Trump on all Iranian ports, in a desperate attempt to raise pressure on Tehran.

Iran has closed the strait to ships from all countries involved in the US-Israeli war since the beginning of March.